High-performance and recyclable epoxy resins based on fully bio-based hardeners containing Schiff base structures

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Chemistry

Background:

• Growing environmental concerns necessitate the development of recyclable, bio-based materials.
• Traditional petroleum-based epoxy resins pose environmental challenges and lack efficient recycling pathways.

Purpose of the Study:

• To synthesize and evaluate novel, fully bio-based epoxy curing agents derived from vanillin.
• To assess the thermal, mechanical, and recyclability properties of the resulting bio-based epoxy resins.

Main Methods:

• Synthesis of two bio-based Schiff base epoxy curing agents: VLYS (vanillin and lysine) and VLEV (vanillin and levodopa).
• Curing of epoxy resins using VLYS and VLEV, followed by characterization of their glass transition temperatures and mechanical properties.
• Evaluation of degradability, reprocessability, and property retention after multiple recycling cycles.

Main Results:

• The synthesized curing agents, VLYS and VLEV, produced epoxy resins (VLYS-E and VLEV-E) with high glass transition temperatures (Tg > 141°C).
• These bio-based resins exhibited superior mechanical properties (Young's modulus >1000 MPa, flexural modulus >2900 MPa) compared to petroleum-based systems.
• The incorporation of Schiff base linkages imparted degradability and reprocessability, with significant retention of thermal and mechanical properties after two recycling cycles.

Conclusions:

• Fully bio-based epoxy curing agents derived from vanillin and amino acids demonstrate excellent performance and sustainability.
• These novel materials offer a promising, eco-friendly alternative to conventional petroleum-based epoxy resins.
• The developed resins show significant potential for applications requiring high performance and recyclability.